The present invention relates to a motor-driven throttle valve which is utilized to regulate the rate of flow of reactive gas for dry etching or C V D (Chemical Vapour Deposition) in semiconductor manufacturing process.
Dry etching or C V D in the semiconductor manufacturing process is carried out in such a way that a silicone wafer is placed in a chamber connected with a system for feeding reactive gas and subjected to react with said gas that is supplied by a supplying system and sucked out by a vacuum pump through a throttle valve. The flow rate of the reactive gas is controlled by the throttle valve according to a desired reaction rate.
However, any conventional throttle valve may suffer sticking of fine particles contained in the reactive gas to an external surface of a valve disc and an internal surface of a valve disc supporting flange and the accumulation of the particles makes it difficult to adequately adjust the valve opening and, in the worst case, makes it impossible to open and close the valve. To prevent this, it is needed to periodically disassemble the valve and carry out cleaning of external and internal surfaces of the valve disc and flange. This is laborious and time-consuming. Furthermore, reactive gases are usually toxic and hazardous to treat.